Higher alkyl derivatives of 2-hydroxypropylisothiouronium salts and their use in sizing paper

ABSTRACT

Higher alkyl derivatives of 2-hydroxypropylisothiouronium salts of Formula I: where Z is -O-, -S- or -NR-, and X is the anion of a strong inorganic acid such as the chloride ion, prepared by reacting thiourea and a substituted propylene oxide or halohydrin such as epichlorohydrin in the presence of a strong inorganic acid such as hydrochloric acid are effective sizing agents for paper and cellulosic products.

Ilied States atent 1 Bremmer et a1.

Nov. 6, 1973 HIGHER ALKYL DERIVATIVES 0F 2-HYDROXYPROPYLISOTHIOURONIUM SALTS AND THEIR USE IN SIZING PAPER Inventors: Bart J. Bremmer, 214 W.

Meadowbrook; Fred J. Meyer, 1 108 Helen Street, both of Midland, Mich. 48640 Filed: May I, 1970 Appl. No.: 33,923

US. Cl 162/158, 162/179, 162/169, 260/584 R, 260/584 C Int. Cl D21d 3/00 Field 01' Search 162/158, 179, 169; 260/584 R, 584 C References Cited UNITED STATES PATENTS 10/1956 Kienle 260/327 R 2,961,367 11/1960 Weisgerber 162/158 Primary ExaminerS. Leon Bashore Assistant ExaminerRichard H. Anderson Att0meyGrisw01d & Burdick and D. B. Kellom [57] ABSTRACT Higher alkyl derivatives of 2-hydroxypropylisothiouronium salts of Formula I:

10 Claims, No Drawings HIGHER,LKYLPEBJYAHYESQE....7a-.. 2-HYDROXYPROPYLISOTHIOURONIUM SALTS AND THEIR USE IN SIZING PAPER BACKGROUND v U.S. Pat. No. 3,272,794. Also the advantages of watersoluble cationic products as paper additives has been recognized such as the cationic polyalkylenimine size of Landes & Reynolds U.S. Pat. No. 2,698,793.

STATEMENT OF THE INVENTION New water-soluble higher alkyl derivatives of 2-hydroxypropylisothiouronium salts of Formula I:

iiflifFeTZ is O S 'or' NR where Range and X is the anion of a s ti'ong inorganic acid have been discovered which have enhanced activity as a sizing agent for paper and other cellulosic products.

These cationic salts are stable in acid or neutral solutions and are readily'sorbed when blended with an size, the aqueous solution is particularly suitable. An appropriate amount of the aqueous isothiouronium salt solution is added to the aqueous cellulose pulp slurry.

aqueous pulp slurry. When the pH of the pulp slurry is then adjusted to about 8-10, they react in situ to provide a water-resistant size. Optionally, the use of a polyalkylenimine retention aid along with the isothiouronium salt provides superior sizing.

GENERAL DESCRIPTION Three essential structural elements of the isothiouronium sizes are (l) the C higher alkyl group, (2) the 2-hydroxypropylisothiouronium salts, and (3) the ether, the thioether or amino group bonding the higher alkyl group to the 2-hydroxypropylisothiouronium (I-IPI) group, i.e.: C alkyI-Z-HPI. Note that when the intermediate group Z is an amine, two types of structures are included: (C alkyl); N-HPI and C alkyl N(-IIPI) and both types are effective sizes.

These isothiouronium salts are readily prepared by reaction of thiourea with an appropriate alkylene halohydrin as described by Kienle U.S. Pat. No. 2,766,256 or Taber et al. U.S. Pat. No. 3,272,794. Alternately thiourea can be reacted with the corresponding epoxide in the presence of a strong inorganic acid such as sulfuric acid, hydrochloric acid or hydrobromic acid.

' The halohydrin or epoxide required for reaction with thiourea are conveniently prepared by reaction of epichlorohydrin and a desired higher alkyl amine, alcohol or mercaptan. Many such'halohydrins or epoxides are commercially available.

The isothiouronium salts are stable in aqueous solution at an acid or neutral pH. If desired, the salt can be isolated by standard techniques, but for use as a paper Then the slurry pH is adjusted to about 8-10 followed by addition of a cationic retention agent such as polyethylenimine if desired, and then the paper sheet.

Under the final alkaline pulp conditions, the isothiouronium salt may react in situ to form the corresponding thiirane which when dried interacts further with the cellulose fibers. Indeed, effective sizing is obtained by prereacting the isothiouronium salt with base to form the thiirane followed by treatment of preformed paper with a solution of the thiirane. Since the thiiranes normally are water-insoluble they are easily isolated and purified. For treating paper the thiiranes are preferably applied to preformed paper as a solution in a chlorinated solvent.

The cationic isothiouronium salts are readily sorbed 1 from aqueous solution bycellulosic materials. They are preferably added as an aqueous solution to the acid or neutral pulp slurry at the beater, stock chest, or other point which permits adequate mixing and subsequent pH adjustment prior to formation of the paper sheet. Alternately preformed paper can be sprayed or dipped in an aqueous solution of the isothiouronium solution followed by treatment with a suitable base and final drying.

The amount of additive applied depends both on the specific pulp and the amount of sizing desired. In general additive concentrations ranging from about 0.0l-3.0 wt. percent based on dry pulp weight are most useful. Optimum sizing is generally obtained with a loading of about 0.1-2.0 wt. percent.

These isothiouronium salts can be applied alone to the paper pulp. But advantageously a cationic retention aid, and preferably a polyethylenimine, such as described in Landes & Reynolds U.S. Pat. No. 2,698,793, is added after the pH adjustment in an amount of about 0.2-1.0 wt. percent. Other conventional additives can Example 1 Higher Alkyl Derivatives of 2-Hydroxypropylisothiouronium Salts A. The following general procedure was used to prepare the isothiouronium salts by reaction of the higher alkyl epoxide with thiourea in aqueous acetone.

A-mixture of 19.0 parts (0.25 mole) thiourea, parts water and about 50 parts acetone was cooled to 0C and 25.0 parts (0.25 mole) 36.5 percent l-ICl added. Then 0.225 mole of the higher alkyl epoxide diluted with about 27 parts acetone was added slowly to the coldstirred thiourea solution in about l.52.0 hr. To complete the reaction, the aqueous mixture was heated at 40-45C for 1 hr. before stripping the acetone under reduced pressure to give an aqueous solution of the isothiouronium chloride containing about forming and drying 3 30-45 percent solids and suitable for use in sizing paper.

By use of 30-40 percent H 50 the isothiouronium sulfate salts were prepared in a similar manner.

B. The solid 2- hydroxypropylisothiouronium salts can be recovered from the aqueous solutions by standard means as, for example, further concentration and then precipitation with methanol or another suitable water-soluble solvent. Recovery of a pure isothiouronium salt was more difficult when the initial epoxide was a mixture with varying C alkyl groups. The structure of the isolated isothiouronium salts was confirmed by elemental and spectral analyses.

C. Further confirmation of the structure of the isothiouronium salts was obtained by conversion to the corresponding thiiranes by treating an aqueoussolution of an isothiouronium salt with a slight excess of aqueous sodium carbonate at -30C. Extraction with methylene chloride followed by drying and removal of the methylene chloride gave 85-95 percent yields of the corresponding thiiranes further identified by elemental and spectral analyses.

Table 1 gives the chemical structure for a number of typical starting epoxides and data on the isolated isothiouronium salts and thiiranes.

Typical test results are given in Table 2.

TABLE 2 SIZING WITH HIGHER ALKYL HYDROXYPROPYL-ISOTHIOURONIUM CHLORIDE lsmhiouronium (oncen- Av. Cl: (RZ-HPI) tration K131i Test Epoxide RZ- Size per Size (sec) 2-1 l-l C, H 0.5 0.3 833 1.0 0.5 103.6 2-2 l-2 (C,,,H= --C .H; )0- 0.5 0.3 84.7 1.00.5 105.2 2-3 l-3 (C ,H -,,-C ,,H,- )-S- 0.5 0.3 62.2 1.0 0.5 104.9 2 -4 l-4 C .H;, N-' 0.5 0.3 64:4 0.5 0.5 68.4 2-5 1-5 (CmHs1)rN 0.5 0.3 73.9 0.5 0.5 88.4 2-6 1-6 (C H -C H:is) 0.5 0.3 1.8 1.0 0.5 1.3 2-7 l-7 (C,.H,-,-C H,,)0-- 0.5 0.3 0.5 1.0 0.5 0.7

" Bis (HPI) Note that the HP] salt of Test 2-6 which lacks an -O-S-, or N- atom between the higher alkyl and hydroxypropylisothiouronium groups and the HPI salt of Test 2-7 with a slightly lower alkyl group are quite ineffective as sizing agents. Similar test results TABLE l.Typica1 higher alkyl hydroxypropylisotlioimmuni salts and thiiranes N0. Higher Alkyl Epoxide Isothiouronium Salt Thii rane yield) ...d \.v 1-1 c..H29o-cH.cH cH2 (1 Chloride, m.p. 94d 87 Sulfate, m.p. 132 d 9 1-2 (C H C I'1 )OCI-I CHCH 2) Chloride, m.p. 9115 '72' Sulfate, m.p. 130d 1'3 w-Hm"- CrnH:z11 O 2 2 C1l10l'lC16(5) 1-4 CntHznN CHz)z Ch10l1d6 61 1-s cud-1 ,N CI-I2CH -CH6 4) Chloride, m.p. e742 72 1-6 (cIz'iigs fjfi gy-cnzcr-i-cn. Chloride, mp. 125-145 (l) Epoxide 44 from Proctor & Gamble, Cincinnati, Ohio. (2) Epoxide 45 from Proctor 8L Gamble, Cincinnati, Ohio.

(5) Not isolated from solution.

Example 2 Sizing with Hydroxypropylisothiouronium Salt (HPI) All beater additive tests were performed with an unbleached hardwood soda pulp having a Canadian Standard Freeness of about 400 ml. To the pulp slurry was added an appropriate amount of the test additive. Then the pulp pH was adjusted to 9.0-l0.0 with dilute NaOH and the retention aid if any added. Handsheets were prepared from the resulting pulp slurry using the general procedure of TAPPI Standard T 205-58 with the sheets being dried in a hot press at a platen temperature of 120C for 4 minutes.

Sizing tests were made at room temperature using a standard KBB size tester and recording the time in seconds necessary for sufficient water to penetrate the paper to carry a current of 80 microamps.

with other hydroxypropylisothiouronium salts have lead to the definition of the essential structural elements shown in Formula 1 above.

The tests shown in Table 2 used polyethylenimine (PEI) as a retention aid. Other water-soluble cationic retention aids including cationic starch and cationic polyacrylamide can be used, but best results have been obtained with PEI as a retention aid in a ratio of about 0.2-5.0, and preferably about 0.5-2.0, parts of PEI per part of isothiouronium salt.

Example 3 Sizing with Higher Alkyl Thiiranes Further evidence substantiating the critical structural elements of the hydroxypropylisothiouronium salts was obtained by examining the sizing properties of the corresponding thiiranes applied as a dip coating with methylene chloride to preform test sheets made from a similar pulp. The test sheets were dipped into a 1 percent methylene chloride solution of the thiirane, the excess solution drained and blotted, and the sheet air dried. Finally the thiirane treated paper was cured at 140-150C for 4 minutes. KBB size tests were made as in Example 2.

Typical test results are given Table 3.

TABLE 3 SIZING WITH HIGHER ALKYL Tl-IIIRANES Av. Concen- KBB Test Epoxide RZ- tration Size 3-1 1-1 C, H,,,-- 0.75 15.0 3-2 l-2 C H C H -,,0 0.188 18.9 0.375 69.7 3-3 l-4 C,, H,-,-,N" 0.047 80.1 3-4 l-5 (C H N 0.188 78.5 0.375 84.9 3-5 1-7 (C,.l-1, C ,H,,)0 0.75 1.7 3-6 alkylketene dimer 0.094 30.0 Bis '(thiirane) Hercules Aquapel 380, US Pats. Nos. 2,627,477 84 2,762,270

1 CH CHCH s= Nnnzx and X is the anion of a strong inorganic acid;

B. Adjusting the slurry pH to about 8-10; and then C. Forming and drying the paper sheet.

2. The process of claim 1 where about 0.1-2.0 Wt. percent of a hydroxypropylisothiouronium chloride is added as the sizing agent'and the paper sheet is dried at about 50l50C.

3. The process of claim 1 where the hydroxypropylisothiouronium salt has the formula:

4. The process of claim 1 where the hydroxypropylisothiouronium salt has the formula:

5. The process of claim 1 where the hydroxypropylisothiouronium salt has the formula:

6. The process of claim 1 where the hydroxypropylisothiouronium salt has the formula:

68 TC .111941 3179 flClisfSifllialaQfla.

7. The process of claim 1 where after adjusting the pulp slurry pH to about 8-10, a cationic retention aid is added before the paper sheet is formed.

8. The process of claim 7 where about 0.25.0 parts of polyethylenimine per part of hydroxypropylisothiouronium salt is added as the cationic retention aid.

9. A cellulosic product sized by the process of claim 1.

10. The cellulosic product of claim 9 sized by treatment with about 0.1-2.0 wt. percent based on dry cellulose pulp of the hydroxypropylisothiouronium salt and about 0.2-5.0 parts of polyethylenimine per part of hydroxypropylisothiouronium salt. 

2. The process of claim 1 where about 0.1-2.0 wt. percent of a hydroxypropylisothiouronium chloride is added as the sizing agent and the paper sheet is dried at about 50*-150*C.
 3. The process of claim 1 where the hydroxypropylisothiouronium salt has the formula:
 4. The process of claim 1 where the hydroxypropylisothiouronium salt has the formula:
 5. The process of claim 1 where the hydroxypropylisothiouronium salt has the formula:
 6. The process of claim 1 where the hydroxypropylisothiouronium salt has the formula:
 7. The process of claim 1 where after adjusting the pulp slurry pH to about 8-10, a cationic retention aid is added before the paper sheet is formed.
 8. The process of claim 7 where about 0.2-5.0 parts of polyethylenimine per part of hydroxypropylisothiouronium salt is added as the cationic retention aid.
 9. A cellulosic product sized by the process of claim
 1. 10. The cellulosic product of claim 9 sized by treatment with about 0.1-2.0 wt. percent based on dry cellulose pulp of the hydroxypropylisothiouronium salt and about 0.2-5.0 parts of polyethylenimine per part of hydroxypropylisothiouronium salt. 